Search engine systems (also referred to simply as “search engines”) are systems that assist a user in finding information that the user wishes to obtain. Today, many of the most common search engines are Internet based and operate in a client-server environment that includes a client system (e.g., a web page displayed by a computer) that enables a user to submit to a search engine a search request. The search request typically includes one or more query terms, and each query term typically includes a word or a phrase. The search engine, in response to receiving a search request, typically compares the query terms (a.k.a. “keywords”) against an index created from a multitude of content items, such as text files (e.g., ascii files), image files (e.g., .jpg files, .gif files), video files (e.g., .mpg files, .swf files, .avi files), web pages, and other content items, and, based on the comparison, returns an indication of the most relevant content items. The classic example of a search engine is an Internet search engine that uses user-provided keywords to find relevant web pages and returns a list of hyperlinks to the most relevant web pages.
For instance, a user may submit a search request to a search engine located at www.google.com (as retrieved on 2 May 2013). In response, the search engine will present a number of results, such as a list of web pages that match the query terms included in the search request, with the most relevant results often being displayed at the top of the returned web page. Similarly, a user may submit a search request to a search engine located at www.youtube.com (as retrieved on 2 May 2013) and receive a list of matching videos.
As the amount of digital data increases, search engine systems are being deployed not only for Internet search, but also for proprietary, personal, or special-purpose databases, such as personal archives, user generated content sites, proprietary data stores, workplace databases, and others. For example, personal computers may host a search engine to find content items stored anywhere on the hard-drive of the computer or in special-purpose archives (e.g., personal music or video collection) stored on the hard-drive.
Given this tremendous growth in the amount of digital data that is accessible to a user, particularly “non-textual” digital data, which we define as digital data that includes non-text data, such as, for example, video data, audio data, image data, etc., there remains a need to improve upon the existing search engine systems.